Question: Moon Jae-in is the head of state of which constitutional republic?
Paraphrase: Which constitutional republic is Moon Jae-in the head of state for?
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P35 wd:Q21001 . ?sbj wdt:P31 wd:Q1520223 } 
Answer: South Korea